Flash, as a non-volatile memory, has become a mainstream of non-volatile semiconductor memory technology recently. A variety of flash memory devices may basically have two types of structure, i.e. stacked gate structure and split gate structure. An over-erasing problem may exist in the stacked gate structure, making the circuit design complicated. In contrast, the split gate structure can effectively avoid the over-erasing effect, making the circuit design relatively simple. In addition, compared with the stacked gate structure, a higher programming efficiency can be achieved in the split gate structure due to the programming via source-side hot electron injection, which makes the split-gate flash memory widely used in various electronic products such as smart cards, SIM cards, microcontrollers and cell phones etc.
In a split-gate flash memory, each split-gate flash memory cell may respectively include a source, a drain, a first control gate, a word line gate and a second control gate, where the source and the drain of each split-gate flash memory cell are respectively connected with a corresponding bit line, the word line gate is connected with a word line, and the first control gate and the second control gate are respectively connected with a corresponding control gate line. That is, each split-gate flash memory cell is generally connected with two bit lines.
A memory may include a memory array and other circuit modules, such as a sensitive amplifier (SA), a decoder and the like. Since an area of the memory array is closely related to cost of the memory, how to reduce an area of the memory array continuously is always a technical problem faced by designers in the memory design.